A PTC thermistor chip which enables easy visual inspection of a soldered portion when it is mounted on a printed board and also enables flow soldering. The chip comprises a first main electrode (12a) and a first sub-electrode (12b) both provided on a first surface of a cuboidal conductive polymer (11) a positive temperature coefficient, and a second main electrode (12c) and a second sub-electrode (12d) both provided on a second surface facing the first surface, with the first main electrode (12a) and the second sub-electrode (12d) and with the first sub-electrode (12b) and the second main electrode (12c) being electrically connected by first and second side electrodes (13a, 13b), respectively.